An example from today

here is one from today. A small pack of 16 cells that will be arranged as 2P8S (because 8S2P is a different arrangement).

50A is expected to be drawn from the pack. The 2 parallel strings share the 50A, 25A each, therefore require lighter connections. But there are three points where the current is at 50A and these are shown with the heavier lines in the schematic diagram.

The output is a heavy gauge wire but at the top of the pack connections are via nickel strips. There is only one place for current to flow in the series connection here and it will receive the full 50A.

To minimise the voltage drops and heat generated over the nickel I worked out we needed 2 layers of 10mm x 0.2mm where there is 25A and 4 layers at the point where 50A flows. Total voltage drop is 132mV and power loss of 5.4W. At this extreme load the cells were exhibiting a 750mV drop each while new, I expect that to increase as the cells age.